Locks and keys are evolving from the traditional pure mechanical locks. These days, there are wireless interfaces for access control devices of electronic locks, e.g. by interacting with an electronic key. Such wireless to interfaces improve usability while electronic key management is significantly more flexible regarding management of access rights compared to pure mechanical locks.
The access control device communicates with an access control server to gain access rights for a particular electronic key. In that way, access for a particular electronic key can be managed centrally by managing the access rights stored in the access control server.
However, sometimes it occurs that communication between the access control device and the access control server fails for a period of time. During such a period, the access control device is unable to check access rights for an electronic key presented to it.